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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

268

GERMAN SILVER

be used for preparing alloys, are sulphur, arsenic and iron. Cobalt which is
always present in commercial nickel to the extent of i~2°/0) copper which does
not exceed i% and the other elements mentioned above, provided these are
present only in small proportions, have no deleterious effect on the technical

properties of the metal.

The following table gives the properties of samples of nickel of different

sources (Lunge, Hollard) :

TABLE   XXXIV
Results of Analyses of Nickel

--------- — ------- -             -        :         i         j                   |       ,         j
									i
				
	CaO
	
Origin.
	Ni
	] Co
	Cu
	Mn
	Fe
	sb!
	As
	Pb
	S
	C
	Si
	Si02
	A1203
	and Alkalies
	P

German Cubes |  ^
	97-08 98-21
	0-89 1-19
	0-15 0-07
	-
	1-22
 0-25
	_
	—
	-
	trace trace
	O-02
 trace
	—
	o-35
 0-24
	O-I2
 trace
	trace trace
	—

Granules from " Kb'nigs-warter and Ebell "  . English cubes   .    .    . " Landore " cylinders .
	98-58 96-86 97-48
	o-75 1-26 1-05 I-7I
	o-io 0-06 0-06
 1-13
	0-91
	0-24
 1-05 o-79 0-58
	-
	trace
	O^O
	trace trace trace trace
	trace 0-09 trace 0-22
	0-26
	O-IO
 0-38
 0-16
	trace trace
 O-22
 0-03
	trace trace trace trace
	-

Unknown origin -! --
	92-58
	I /i 0-94
	3-77
	1-49
	0-31
	0-04
	trace
	
	trace
	0-18
	—
	0-39
	0-14
	trace
	0-05

French coinage i   .    .
	97-75! i'587
		0-102
	—
	0-259
	~~
	
	I"
	
	
	
	
	
	
	

Electrolytic nickel
	99-22
	0-71
	O'OI
	0-046
	
	
	
	
	
	
	
	
	__
	____
	

GERMAN   SILVER
(Argentan, Packfong, Alfenide)

Owing to their colour and stability, these alloys are used for domestic
articles, for ornaments in place of silver, for coinage, etc. They all consist
essentially of copper, nickel and zinc, sometimes with small quantities of
lead and iron and, in rare cases, tin and manganese. Other alloys of similar
appearance, used for coating rifle bullets or for coinage, consist of 70-80%
Cu, 20-30% Ni, and small proportions of lead, iron, zinc, etc.

The analysis of german silver and of copper-nickel alloys in general is
carried out as follows :

A. Electrolytically 2

In a small covered beaker, 0-5 gram of the alloy is gently heated on a
water-bath with 15 c.c. of nitric acid (D 1-2), the solution being subsequently
diluted with 20-30 c.c. of water. Turbidity indicates tin, which is deter-
mined as in i; a perfectly clear liquid is, however, used at once for the
determination of copper and lead (see 2).

1. Determination of the Tin.—The liquid is evaporated to dryness,
the residue taken up in a little water and a few drops of nitric acid and the
liquid heated for some time and filtered through a compact filter-paper
into a 300 c.c. beaker. The precipitate is washed first with hot water
slightly acidified with nitric acid and then with water alone, dried, ignited
in a porcelain crucible and weighed : Sn02 X 0-7881 = Sn.

1  The nickel supplied to the Italian mint for 0-2 lira pieces must contain 97-50%
Ni and not more than 1-5% Co, 0-8% Fe or 0-5% of other impurities.

2  Belasio :   Annali Soc. Chim. di Milano, 1908, XIV, p. 244.                                                                                                                           •                                        ^,1